That's the best title I could come up with, but I'm not sure it describes my question. Heck, I'm not even sure I can express it well enough to communicate, but here goes.

I am of the belief that sufficient pattern DENSITY, at a sufficient velocity and with sufficient pellet mass, is what kills birds and breaks targets. In other words, if the velocity and the mass of the pellet(s) is enough (retained energy), density in the pattern is what puts the shot on the bird. Greater density, greater number of hits on target, provided the target is within the pattern area.

If that is so, then the same pattern density delivered from a .410 will kill and break a target equal to a 12 ga. Don't get riled up yet, I'm going to qualify that. If the same pellet size is used, at the same velocity, and the pattern density is the same, the bird will not know if it has been hit by a 12 or a .410.

Now, as to pattern density. It is absolutely truthful to say the above can be done, and is done. But, at what cost? Pattern size. The density of a pattern fired from a 1 1/8 oz. load can equal the density of one from a 11/16 oz. load at the same distance, if greater choke constriction is used in the .410 to accomplish this. This, again, reduces the overall diameter of the 11/16 oz. pattern and makes putting that pattern on target more difficult.

So, if I haven't been tried and convicted of heresy yet, how can this be calculated? Have charts ever been published that show, for example, what diameter the pattern from a 11/16 oz. load of #8s would have to be to equal the density in a 30" pattern from a 1 1/8 oz. load of #8s (100% patterns)? I'm not much at math, admittedly, but I know many of you could quickly calculate this. I also may not have done a very good job of communicating this, and please feel free to cover any variables I may have missed. But, hopefully, charts exist somewhere showing these comparisons.

SRH

Stan, IMO, uou have communicated a good question very accurately! The answer is a qualified "Yes." I say qualified because the calculation is not simple, not at all. The reason is that patterns never have a uniform distribution of shot. The pattern always exhibits a Rayleigh distribution; the same distribution as governs bomb patterns, artillery fire, and rifle fire. It is fair to think of a shot pattern as a "bunch of rifle bullets all fired at the same time." Rifle fire would make a smaller pattern, but the distribution within the pattern would be the same 'ole Rayleigh distribution.

We can make a passable SWAG (note that this is not the real statistical calculation, but it will do for illustration) by saying that the .410 will have about 11/18 (11/16 / (18/16)), that is 61%, of the effective area of the 12 bore. Lets say, for grins, that at the distance and with desired choke, the 12 has a 24" effective diameter; that is 452 square inches. The .410, then, has 61% of 452 = 276 square inches. The radius for 276 is the square root of 88, which is 9.4 inches. So, the diameter is 2 X 9.4 = 18.8". Note that your aiming error with the .410 must be not worse than 78% of aiming error with the 12 bore. As you can see, the situation for the .410 is not as bad as is often presumed.

Hope that helps. BTW, post back if you need more detail with the math.

DDA

Stan, in the calculating of patterns whether it is a .410 or 10 gauge, the percentage is achieved by how many pellets are in a 30" circle at 40 yards. In order to get the percentage, the amount in the circle is then taken by how many pellets are in that load to begin with, whether it is #9's or #4's.
Both the .410 and 10 gauge can have the same percentage.

"If that is so, then the same pattern density delivered from a .410 will kill and break a target equal to a 12 ga. Don't get riled up yet, I'm going to qualify that. If the same pellet size is used, at the same velocity, and the pattern density is the same, the bird will not know if it has been hit by a 12 or a .410."

I think everyone will agree with that. It is all about putting the shot where it counts.
I did you did a good job explaining your point.

Stan,

in theory this is absolutely correct.

The practical application, however, has its limits. One could kill game with a .410 as far as with a 12, if one could get a .410 to pattern as densely as the 12 (at the expense of a smaller killing circle). The "if" is a big question. I have known people who tried to achieve this pattern density with 20s and .410s, claiming that this would make their shooting more sporting. None of the attempts were successful. Besides, all experiments with extra long shotgun ammo known to me suggest that the tighter the pattern is, that is, the less space there is between individual pellets, and the more bulletlike is the pattern in behavior, the less predictable is the flight. One is bound to get problems with POI to POA consistency, for instance.

So, while the theoretical reasoning is flawless, I doubt that in real life anyone can kills with a .410 as far as with a 12 bore.

There is also the fact that patterns deteriorate at an exponential rate and though their 'silhouettes' may be similar in shape they will not be in density at any significant similar distance from the muzzle. Speaking here of differing charge weights of same size shot. Nonetheless, there should be a point [distance from the muzzle] that pattern effectiveness is similar from one gauge to another though they will be dif from one to another in distance. That is the comparitive 'sweet spot' or equality point that you are referring to.

I do not think it is any more easily arrived at mathematically than a pattern can be forecast. That random behaviour within parameters [observed limits?] is always going to remain proximate, rather than exact.

The likely reason there is no such chart existent is that the nature of the problem is not wholly linear. Lest I have confused anyone, I do not argue your thinking at all, Stan. However, aside from some extensive empirical pattern testing with the specific loads & guns you might wish to use, knowing the exact range where that 'sameness' exists for both guns & loads would at best be a SWAG. And then what are the odds of encountering game or target at the exact desired range?!

It is much easier to simply limit shots taken with <3/4oz. payloads to inside 30 yards & use shot of sufficient size for the intended target. 3/4 oz. payloads [not only in 28's, but 20's & 12's too] can & do put mourning dove & other upland birds in the bag & break bunker targets at ranges of 35yards + with what would seem disportionate regularity. Brister was quite intrigued with that observation in regards to the 28 ga. & went to some length to find out why it was the case & wrote a book on the subject. Was it difinitive or absolute? Yes & no. It did shed a lot of then new & interesting light on the quest for an answer. He did not, that I recall, ever ask nor speak to your observation.

I'd call it an observation more than a question and a valid one, but I have no expectation of seeing an equivalence chart of assorted gauges vs. range anytime soon, though I guess someone might play with it on an X/Y axis using a linear regression from a lot of testing & data points & come up with a rule of thumb kinda thing. Not sure what one would do with it if it existed.

No doubt, you could likely publish your findings in an article of interest as Sherman Bell has done. I dunno whether I'd call it a potential hornet's nest, a pinata or a can o' worms;-);-)The validity of your observation is real enough, however the proof in any absolute graphic is problematic.

Best, tw

Good points, and I do recognize the problem with shot stringing and pattern degeneration in the .410 especially, due to a higher percentage of the pellets being deformed due to setback, etc.

My idea is not to try and make the .410 equal to the 12, or any gauge in between, but to have a means to say, within reason, "Okay, I know how far I can dependably kill a dove with my 20 ga., 7/8 oz. of 7 1/2s and .020" choke. At what range do I need to turn down a shot with my .410, given that it has .032" choke and I'm using 11/16 oz. of the same 7 1/2s. Again, I'm asking about pattern density only, and I know how hard it is to keep shootability, shot stringing, moon phases and the constant shifting of magnetic north out of the discussion. And I am not belittling any of those real or perceived influences, just trying to get to the actual numbers.

You're right that each gun is different, and is a rule to itself. But, that doesn't keep every gun related outfit that comes along from publishing their own version of the "choke chart", showing what the constriction of each commonly referred to choke is actually dimensioned. We saw that in a recent thread. Is this any more difficult to determine than that?

Miller, I know you could tell me what the method is to determine this. Couldn't one simply determine the number of shot in the payload and use the square inch area of the pattern diameters to get a comparable density? Help me determine the formula(e) to use and I'll make the blasted chart myself!

SRH

"IF" shot distribution was uniform throughout the pattern this would be very simple to calculate. Given the same choke percentage the 1 1/8oz load would have the same density as the 11/16oz one at 28% greater range. To have equal density the 11/16oz would have to make a 100% pattern at the range the 1 1/8oz made a 61% pattern.
It is of course not quite this simple as R'Man pointed out. There is even a bit of evidence that the pattern from a smaller bore might have more of a tendency to central thickening than the larger bore. "IF" this be true then the 100% .410 with 11/16oz could have a slightly greater range than the 61% 1 1/8oz on a perfectly centered shot, but the larger gun would have a better fringe area.

Another fly in this admittedly interesting jar of ointment: you can't go by "book" figures to obtain accurate pellet count in a given load. Before you base your assumptions on 350 7 1/2's per ounce, you need to check each individual brand of shell (even from the same shotshell maker) to see how many pellets you have. The "book value", I've found, is just a rough average. I've found 6's--talking supposedly American 6 here, not the smaller British 6--that count out around 200/oz; others close to 250. On either end, that's a 10% deviation from the "book" number of 225. And really bad news if you're comparing the two extremes. Likewise, I recently counted Rem Gun Club and STS 20ga 7/8 oz 8's and found a significant difference there as well.

Obviously, if you're going to compute density accurately, you can't just assume that the load in question contains the number of pellets it should contain based on "book" figures.

That's the numbers I'm talking about, Miller. Thanks, now how'd you get them?

SRH

Stan,
All said and done...and as others have alluded, given all the variables of ammunition, forcing cones, choke cones and whatever else I didn't think of, I think empirical exploration (pattern testing) along with a rough SWAG, is going to accomplish what you want in a much more expedient manner and with greater accuracy. From that data, you could build a chart.

I've had some 3/4 oz and 11/16 oz .410 loads that had great pattern distributions and some that didn't in various guns for various reasons, most of which I never figured out, but only speculated. As I'm sure you're aware, the .410 is a fairly fickle firearm. I love 'em.

I may be completely wrong, but if you load a 3/4 oz. load in a 12ga. and a 28ga., for targets only, out of two guns that throw the same % patterns would it not be more a question of the dynamics of the two guns than the gauge?Mark II

Stan, if you really want to get into testing, download a copy of Dr. Jones's "Insights" program for digital acquisition (from a digital photo of a pattern) of patterns and statistical analysis of them. Matter of fact I would recommend anyone considering patterning work use Insight. It is a fabulous tool. Post back if you want to go this route and/or need help with it.

DDA

Thanks, Don, and all. First thing I need to do is get off my butt and get that pattern plate built, then I can photograph the patterns instead of keeping all that paper. I can understand the numbers much better now.

SRH

Stan;
My figures were simply theory & based on a situation which doesn't exist in the real world. If the shot were distributed evenly over the entire pattern & spread linearly it would be a simple mathamatical equation to calculate on the fact the area of a circle is proportionate to the square of its diameter. The fly in the ointment is the shot are not evenly distributed. In theory if you had 100 shot in the 30" circle & you drew a concentric 15" circle then it would have 25 shot in it. You could no doubt fire a million patterns & never acheive this situation. You will virtually always have some amount of central core thickening which will increase the number of hits in the center, but lessen the hits in the outer ring. If you ended up with 40 hits in the 15" circle & 60 in the outer ring then you would have 200% central thickening so obviously a well center target coud be killed or broken at a further distance than one in the outer ring. Yet each of these two patterns could be described as a 60% pattern with 3/4oz of #6 shot.

Thanks, Miller, I understand that, and have been aware of the "hot core" of nearly all shotgun patterns for as long as I have been patterning, which has been a long time. I understand the inability to calculate an exact comparison, because of this and because of the way shot are distributed, as Don explained. But, this question still nags me. If this is the case, and we accept that it is, can we not then go forward with a comparison that accepts the error, and the fact that none of this is exact, and have something useful anyway?

When I study published yield comparisons of corn, cotton or peanuts for the previous crop year in order to determine which variety, out of dozens, I will plant this spring, I know that these same varieties could be planted and compared again and the results would not be exactly the same. The top yielder might fall to second, or third place. But, when I look at those yield comparisons for the past three consecutive years I see one or two emerge as the clear leaders, I know I have some information that is useful to me. At the bottom of the page of corn yields there will be info such as this, showing yields at various locations:

Yields ----------297.3, 312.2, 314.2, 265.6

LSD at 10% level ----9.4, 16.1, 14.6, 18.4
Std. Err. of Entry Mean 4.0, 6.8, 6.2, 7.8

I'm sure these two lower lines of numbers mean much more to some of you than they do to me. I understand, by this, that these yields can be given a certain level of credibility. If this is acceptable to me I put my "faith" in these results.

Is there a difference here that I do not see? I certainly am no student of "probability". There may be some of you who are, and understand these things much, much better than I. If so, please comment.


SRH

Took me a while but I finally figured out....check you your pattern on a pattern plate if it looks good you're good to go.

Time spent analyzing patterns could be better spent.

10% LSD sounds bad to me, but if you look at enough patterns, you may well be tempted to use the stuff.

Stan;
I would guess that this would be possible, but will have to say I have simply not done enough pattern testing at a level to make any real conclusions. One question in my mind is if a similar shot loat is fired through different bore sizes, can a statistical probability of pattern distribution (basically central core thickening) be established. In my mind, I would expect the largwer bore to give less core thickening than the smaller bore, but have not actually proved this to be the case.

That might hold true until you really squeeze the choke on a big bore.

With this greater understanmding of numbers any one care to comment about ethics of shooting at birds with shotgun at at 100 yards or more ?

Shooting birds at 100 yards has more to do with someone being an idiot than it does with ethics....

Simply looking at two dimensional patterns ignores the three dimensional aspects of a shot string. Greener's book has a wonderful section on dragging a long paper target on a rolling trolley to estimate the length of the shot string in 1910 technology. I've since since other writers use modern photography to illustrate it. While a gap or hole in the 2-d pattern is certainly proof of an identical hole in the 3-d pattern, the converse is not true, i.e. a "no hole" in 2-d cannot be assumed to be proof of "no hole" in 3-d--the pellets may have arrived at completely different times. Somebody probably has more current info on this factor than I do. Just food for thought.

Nope.

SRH

Sounds like a subject for an different thread rather than hi-jack this technical discussion with a morality discussion. Dave has allocated plenty of server space for another thread.

100 yards, think I'd want a feather-seeking Stinger missile.

I think I have "seen the light", concerning this. The chart I want really cannot be valid without lots of replicated patterns. I can build my pattern plate and shoot all the patterns I want, and arrive at my own conclusions.

Thanks to several of you who pointed that out. It really sunk in for me when I used the corn yield example. Replicated tests are absolutely necessary to have any useful data there, too. Once a farmer, always a farmer, I guess.

Thanks all, SRH

"##@%&$%@#&^" Imagine me red in the face pounding my desk!!

Guys, A very bright guy gave us, I repear, GAVE US, the tool to do exactly what Stan seeks to do. All we have to do is use it; For FREE!! Stan, youse is plenty schmart to do it, too. It does require some effort. But, I repeat, BUT, it will answer above patterning questions without systematic error. Yes, I speak of Insight; very appropriately named, it is, too. If I didn't have too many projects on my plate, I'd do it. I do, so I can't. However, I will most gladly coach anyone willig to work on this project. Stan??

Ok, pardon the rant. Before Insight, such a question would have required an unrewarding amount of work - I know because I started with a hand done analysis system; it worked, but was too labor intensive.

The ethic of shooting (at) any bird at any distance is not based on the distance alone. The ethic is knowing you have sufficient pattern density of shot with sufficient retained energy and sufficient aiming error allowance to humanely harvest said bird. That is to say, put a lethal dose of shot in the same airspace as said bird. The actual yardage is not significant if you know your gun/load's real world performance and your real world aiming performance. Some people are bad enough shots that there is no ethical distance for them on live birds.

IMO, the better question is, "Does anyone know a choke/load that might be useful at 100 yards?" I don't, but would not rule out the possibility.

DDA

Bob Brister's more modern version of this involved his wife towing a target sled behind the family station wagon while he shot various loads at it from various distances, and compared to stationary patterns shot with the same loads at the same distances. String isn't a huge factor at skeet distances, nor at the distances most upland birds are shot. Much bigger factor for the really long range stuff. However, if you're talking waterfowling, that's a different story entirely because while a lot of waterfowlers would rather shoot lead than steel, one advantage steel does have is that it reduces string significantly.

Don,

Please PM me with a phone number and we will talk about this some. I'm interested.

Thanks, SRH

Stan,
Being of the same caliber interest as you, let me know if I can help.

Stan
I am as dumb as it gets when it comes to this math but from exsperience a .410 is very humbling, to me it was because of the lite weight of the gun as well as the load, but you need to order the book Sporting Guns and Gun Powder by Frederick Toms. It was reccomended to me last week by someone on double gun.It is an awesome book full of all this useless info you are talking about.Numerous experiments!

I used to get all excited about patterning until it finally became obvious to me that 2 dimensional patterns have only a loose correlation to what the target experiences as the shot cloud goes by.

Zutz and Oberfell and Thompson all have serious pictures of patterns with obvious holes in them. Zutz holds a clay target over the pattern void to illustrate the concept that a target can slip right through there without so much as a nick.

Well... during the passage of the shot cloud the target moves, unless of course you only shoot at fixed paper sheets.

No moving target ever sees the same pattern as you see on a pattern sheet unless the only motion is directly along the shot flight axis.

Shotgunning is an exercise in probability not unlike gambling.

A few patterns are useful to illustrate the range limitations of the load, and yes it's directly and most importantly related to overall density and not so much to perceived distribution.

Your target is moving through 3D space, it experiences a passing swarm of shot, and the path it takes through the cloud and how many pellets it might collect on the way is at present not measureable.

Burrard also did extensive testing on this using a large steel plate mounted on the side of a "Lorry". After reading through all his detailed descriptions consisting of numerous pages & illustrations the bottom line was basically a 40/40 situation.
The 40/40 term is mine not his but it boiled down to on a bird/taget moving at 90° to the shot line if it does not exceed 40 yds range & is flying no faster than 40 MPH just shoot, DON'T WORRY about the 3-dimensional Shot String. Under these conditions the elongation of the paterns were so slight as to be essentially meaningless. He of course only tested the 12 ga, might not hold true for a .410.
A target moving at any angle other than 90° to the shot line would of course have even less sideways movement across the shot line than the 90° one. For the most part for anyone other than extreme range pass shooters, speaking of shot strings mostly just clouds the issues & causes undue concern. As Nash Buckingham so elogantly put it the main thing is to "HIT" the bird.

Agreed Miller. I've read both Brister and Burrard and their data is similar. As I recall, Brister makes more of a deal of it.

The thing that struck me is that target motion takes your neat little 30" circle and makes it an ellipse from the viewpoint of the target.

A target with a crossing velocity component of 30 MPH equates to 528 inches/second. A six foot shot string at 800 fps passes the target in .0075 second. During that time the target moves 4". Does not sound like much, but that's 13% of the diameter of the commonly used 30" patterning circle.

It sort of makes the guys holding a clay target over a pattern 'void' look silly.

It's a crap shoot how many pellets a target might collect out of the shot swarm, but as you indicate the first order of business is to give your pattern a chance in the first place.

"A few patterns are useful to illustrate the range limitations of the load, and yes it's directly and most importantly related to overall density and not so much to perceived distribution." see above


SGJ, no meaning to jump on you, but there seems to be a point you are not understanding. Densities along any given radius of a pattern gives the distribution. Knowing the distribution allows you to calculate the probability of hits. If you have distribution at a range, it is possible to project forward and backward in range. This is what Stan is looking for. Insights gives us all the capability. We only have to learn the procedure and do the work. I'm not saying it isn't a considerable amount of work, rather that a near miricle of data is possible by doing it - data that was unthinkable a few years ago. Yes, target movenent within the pattern appears to blur the results. But, since this is a game of probability, the "loss" of the target moving out of the effective diameter of the pattern is off-set by it moving deeper into the effective diameter on the other side. It is not an issue to negate the value of patterning with digital analysis and statistical output.

No offense meant in any way, no how, at any time!!

DDA

It is so hard not to make statements like this, because so often we think linearly and do not take all shot angles into consideration. That statement is probably true for crossers. But it absolutely is not true for straight incomers or going away birds! Shooting as much as I do, I see a lot of both of those, lots of incomers on a dove field, and a sporting clays course. Lots of going away quail, sporting targets and again, doves. A two dimensional hole in a pattern can very easily cause a miss on birds like these.

I once saw a Browning 2000 that came from the factory shooting the most perfect donut patterns you ever saw. I mean every time. We patterned it after the owner's hit percentage tanked after buying it. A slight honing of the choke by a gunsmith straightened it out. Don't tell me a hole in a pattern can't cause misses, "I done seen it happen".

SRH

No offense ever taken, Don. I'm not like that.

I think we're trying to say the same thing.

By distribution, I was referring to the 'patchyness' as the term was used by O&T.

This would seem to be the only reason to ever pattern a load or a choke.

The capability to do 3D pattern analysis would be most interesting. Until this is available, I've shot my last pattern plate!

Barrel experts who do pretty extensive patterning when 'competition' choking shotguns, such as Eyster, would undoubtedly disagree with you. I, for one will continue to pattern my guns in 2D until something better comes along, which is unlikely anytime soon, IMHO.

SGJ, thanks, I'm kinda "debdey" by nature and some take offense at me. Glad we can talk openly.

Distribution is a very different meaning/definition to me in this case. I'm using the statistical definition of how a statistic (in this case pellet hits per sq inch or sq inches per pellet hit) varies with pattern radius from center to edge. No pellet will hit exactly center, so, the hits/sq in at center is zero. However, as you move even a little off center, the hits/sq in will go to the maximum and then taper off. Shotgun patterns follow the Rayleigh distribution - remember the more famous Normal distribution frequently refered to as the bell curve? Well, the Rayleigh looks like the bell except that it takes a very sharp dip from max to zero at the center of the pattern circle. Remember "center thickening?" That is slang for the high values of the distribution near the center. The difference between "center thickening" and the "Rayleigh distribution" is that the distribution gives you hits /sq in which can be related to lethalness of the pattern. Matter of fact, you get a very good picture of the diameter of the effective part of your pattern as opposed to the overall diameter of the pattern. "Central thickening" simply tells you there is more shot per sq. in. toward the middle of the pattern than toward the edge. Remember I said the pattern can be predicted for greater and lesser ranges? Well, that is the beauty of this method.

Off topic for a moment, folks, but I'm sure you'll understand. Rocketman, I sent you some hard-copy mail and had my letter returned. If you still have my email address, I'd greatly like to hear from you and re-establish contact....

Just a point of thought that is contrary to the prevalent low velocity loads popular on this site, but the discussion about how long the shot string is, terminal velocity, and crossing target speed, seems to make a case for higher terminal velocities.

W/o opening too large a can o' worms, there is a lot of useful information here:

http://www.bunkershooting.com/ReloadingForBunker.html

I'd suggest one review the whole site, lots of good information there, arrived at through no small expense. Do enough screwing around [testing] at the grease plate/pattern board & shooting bunker & powder pigeon & you can come to similar conclusions.

Also, Lyman in one of their maunals offers some really good downrange ballistic data on lead pellets, the gist of which says that by 40 yards most target sized shot is travelng at similar velocities irrespective of muzzle velocity & if you want to deliver more energy for game or target purposes, use a larger size shot.

Was Burrards gun barrel stationary ?

Chuck, I think there's something in that post I'm not getting. Lower velocity does not necessarily mean longer string. In fact, if you add too much velocity, it can actually result in longer string caused by a higher percentage of damaged pellets. Certainly, on long crossing targets, lower velocity can require more forward allowance. But that doesn't have anything to do with string.

No; He had a long plate mounted with an aiming point marked & swung on it as an assistant drove it by at a measured distance & a fixed speed. He could not of course with this method get a fixed pattern & a moving one with the same shot, but did do extensive patterns on a fixed plate for comparsion to the moving ones, with same gun & load of course. I don't recall exact figures now, but his testing in comparsion also to other testing which has been done over the years showed that about 75% of the total shot was in about the front 40-50 % of the sring, with the badly deformed shot making up an extended tail. Consequently it does not follow that if a given load advertizes a 30% reduction in shot string, that this converts to 30% more pellet strikes on the target. Burrards testing was all done with shells using un-buffered, un-plated shot with card & felt wadding. He still found shot stringing to be of little concern within the 40/40 parameters, which accounts for the vast majority of shotgunning. It does of course make for Extremely Good Advertizing Hype.